Side by side
KaiMail vs Relais
Both stand on email forwarding services. Which one you can start free with, which one lets you read the code, and what each costs once you pay.
Free plan APIWeb
KaiMail combines custom-domain forwarding, webhook delivery, and API-based sending. Check the plan limits and technical setup requirements against the volume and integrations you need.
Visit KaiMail Free plan Self-hostedWeb
Pick Relais if you want to use a custom domain with your existing Gmail for both receiving and sending, or want to self-host the same feature set. Look elsewhere if you need delivery to continue after the trial without subscribing to the managed plan or running the self-hosted version.
Visit RelaisThe facts
| KaiMail | Relais | |
|---|---|---|
| Free plan | Yes | Yes |
| Open source | Not published | Not published |
| Runs on | API, Web | Self-hosted, Web |
| Lowest paid plan | KaiMail Plus: ¥550 a month | Managed: $5 per account a year |
| Plans published | 4 | 2 |
| Maker | Not published | Not published |
| Website | kaimail.net | relais.sh |
| On email forwarding services | #9 of 25 | #13 of 25 |
KaiMail: what it does well
- Forwards incoming email with ARC and DKIM signing.
- Webhook delivery includes signatures and retries.
- Sending API provides tracking IDs and status checks.
- Free plan includes one domain and mailbox.
- Supports email events sent to HTTP endpoints.
What to know first
- Free plan is limited to 300 emails monthly.
- Support is provided exclusively via email.
- DNS and webhook setup require technical knowledge.
- Webhook attachments are retained for seven days by default.
Relais: what it does well
- Delivers inbound mail directly to Gmail via the Gmail API.
- Supports outbound mail through Gmail Send As.
- Managed plan includes DNS verification, delivery logs, and monitoring.
- Trial gives full feature access for 14 days without a credit card.
- Managed plan allows unlimited domains and email addresses.
What to know first
- The managed plan costs $5/year for each Gmail account.
- Self-hosting requires your own infrastructure.
- Email delivery pauses after the trial if you do not subscribe.
Alternatives to KaiMail Alternatives to Relais The whole list